Improving braking performance of long reach Tektro R559 calipers?

Question

I've been gradually restoring an old Fuji 3-speed, and I'm looking to improve the braking performance. Right now, if I have any speed at all, I feel like I can barely get enough braking power to come to a stop. In particular, the rear brake feels very weak.

I installed Tektro R559 calipers. The rear wheel has an aluminum rim (27") which I expected would improve braking performance but the rear brake feels much weaker than the front. Currently, I'm still using the original Dia-Compe levers, but I'm wondering if replacing the levers with new levers like the Tektro FL750 would improve the braking performance, or is there a better model/style of lever I should go for? I can't tell from the product specs if the Tektro FL750 would have better geometry/pull for the new calipers, as compared with my original Dia-Compe levers. What are the specs that I should look for in new levers to maximize braking power? I am also considering replacing the cables/housing (should be done regardless of whether or not I change the levers), so any recommendations on housing is also appreciated.

Last question: the front wheel still has the original steel rim. Should I replace the brake pads on the front with something "steel specific"? Or would you recommend I replace the steel rim with a new aluminum rim?

Here are a few photos:

Update: I have replaced the brake housing and cables (Shimano Universal Brake Cable Set), as well as installed new levers. For the levers, I decided to go with Velo Orange's Grand Cru short pull levers. The brake performance was dramatically improved with the new housing. The old cables didn't slide smoothly in the housing, reducing how much force was getting applied at the wheel. The new cables/housing account for 90% of the improved braking performance. The new levers feel lovely and are very crisp, with no lateral play. I'm sure I could have gotten cheaper levers that work similarly, but these levers are a delightful treat/upgrade. I adjusted the calipers so they're as close to the rims as possible without rubbing, and the short pull levers ensure I'm getting plenty of force when I squeeze the levers even just a little bit. In the future, it would be nice to replace the front steel wheel with an alloy rim to further improve braking performance, but for now I'm happy with the braking performance, and it's probably "good enough" for the kind of riding I use this bike for (mostly flat urban environment, never at very high speeds, with only occasional rain).

Answer 1

Right now, if I have any speed at all, I feel like I can barely get enough braking power to come to a stop. In particular, the rear brake feels very weak.

You failed to explain why it feels weak.

There are two reasons for a brake to be weak:

1. You need unacceptably high hand force to get the desired braking
2. You pull the lever so close to the bars that it's hard to squeeze it anymore due to the changed geometry

If the brake is weak for reason (1), then you need brake levers with more mechanical advantage. I'm not sure what the mechanical advantage of your brake levers is. Unfortunately, this is not something that brake lever manufacturers openly tell. You could buy some brake levers, but you don't at all know what mechanical advantage you are going to get.

However, generally the trend in levers has been towards slightly increasing mechanical advantage, so more modern levers could be worth trying.

Note that generally there are two approximate pull ratios: long pull (for V brakes) and short pull (for calipers and cantilevers) but the exact pull ratio differs from lever to lever (so two levers in a same category won't be the same), so pairing V brake levers with caliper brakes could create an issue where you can't get enough braking force even if you squeeze the lever very hard. However, an old bike is unlikely to have V brake levers. Nevertheless, if you buy new levers, you have to buy short-pull levers, not any long pull / V brake levers. Finding flat bar short-pull levers today could be tricky because it's all long pull for flat bars today.

If the brake is weak for reason (2), it may be that the calipers themselves are at fault, or the cabling system could have too much flex. The problem of long-reach caliper brakes is that they flex a lot, because the caliper arms need to be long and the longer a beam is, the more it flexes. Unfortunately, in this case you don't have any good solution. Cantilevers and/or V-brakes could be a solution but if your frame has caliper brake mounts, most likely it lacks the cantilever posts that are needed for both cantilevers and V-brakes.

However, on mechanical brakes first diagnosis of (2) should be whether the brakes have correct pad clearance. So if the brake pads are too far away from the rims, adjust the cable tension using the barrel adjuster first and if that doesn't have any adjustment range left, you may need to re-clamp the inner cable at the brake. Also checking that pads are correctly aligned against the rim can help, because if the pads only partially touch the rim, it can cause too much flex.

Racing bikes use so ridiculously short-reach brakes that you probably can't fit anything more than a 23mm tire, and forget about mounting fenders. The reason for this is that such brakes can be made very lightweight and stiff (free of flex) at the same time unlike long-reach brakes which usually can be neither. Fortunately today this is changing due to introduction of disk brakes, but unfortunately disk brakes suffer from issue (2), i.e. the brake system may have too much flex to have acceptable braking. With even perfectly bled disc brakes, it's very easy to move the lever very close to bars, making it impossible to brake with such great force that the rear wheel rises from the ground unless the cyclist is very lightweight.

Note that solving issue (1) will make issue (2) worse, so if your levers have too much mechanical advantage, they will touch the bars and you are unable to get the required braking force.

As for cables and housings, forget any no-name supplier and choose the genuine one, Shimano. They have SLR housing for short-pull brakes (calipers, cantilevers) that are dimensionally stable under huge forces and M-system housing for long-pull brakes (V-brakes) that has low friction needed for long pull. Also Shimano inner cables are of very good quality. Pick only stainless steel inner cables.

Steel rims shouldn't be used in the wet. You will have terrible braking with almost no recovery even after many wheel rotations.

As for brake pads, generally Kool Stop Salmon is considered one of the best. I understand Swiss Stop BXP is also very good. But most cyclists who use them use them on aluminum rims, I have absolutely no idea how these work for steel rims.

If the brake pads are old, they could have lost their friction coefficient and installing any brand of new brake pads could improve braking.